1. Field of the Invention
The present invention relates to a method for encoding/decoding of digital data, and more particularly to a method, in a digital-video home system (D-VHS), for the encoding/decoding of digital data by utilizing data shuffling.
2. Description of the Prior Art
In a magnetic and optic recording system such as a digital phone, a digital video cassette recorder and a digital compact disc, scratches or fine dust results in frequent occurrences of burst errors having a long error length or partially concentrated errors.
In a system having a high possibility for burst error, a Reed-Solomon (RS) coding method has been widely used and recognized as a powerful error correcting code. According to this coding method, before transmission or recording of digital data, outer parity information and inner parity information generated by an RS coder are added to the digital data. The added outer parity information and inner parity information effectively serve as a powerful tool to correct errors occurring during transmission or recording of digital data upon receipt of data or upon reproduction of data by an RS decoder.
Data shuffling has also been used to provide more powerful error correction. Generally, shuffling means a method of scrambling digital data in a time axis upon recording the digital data onto a recording material such as a magnetic tape. As a prior art relating to a shuffling of digital data, U.S. Pat. No. 5,301,018, entitled `METHOD AND APPARATUS FOR SHUFFLING IMAGE DATA INTO STATISTICALLY AVERAGED DATA GROUPS AND FOR RESHUFFLING THE DATA`, issued to Peter Smith and two other inventors, was disclosed. In accordance with this art, to equalize the information content of the data prior to compression, the video image is divided into a plurality of image representing blocks and a predetermined number of the image blocks from different spatial locations in the image to form a succession of data sets representative of the video image information. There are various prior arts relating to data shuffling, including U.S. Pat. No. 5,321,748, entitled `METHOD AND APPARATUS FOR TELEVISION SIGNAL SCRAMBLING USING BLOCK SHUFFLING`, issued to David E. Zeidler and John T. Griffin.
However, these prior arts do not disclose a coding technique based on the D-VHS. The D-VHS is a new digital data recording art based on a video home format where compressed information such as digital broadcasting data can be recorded. A technical specification of the D-VHS was mainly prepared by the JVC company of Japan in 1995. The D-VHS is a bit stream recording/reproducing apparatus where compressed or processed digital data is recorded directly in a tape without additional processing of data and is reproduced from the tape. A bit stream recording unit does not integrate functions of analog/digital conversion, digital/analog conversion, digital compression/decompression, or descrambling.
Consequently, to accomplish a purpose of improving an error correcting ability in the D-VHS, a new data coding/decoding method is required. For this, a method employing data shuffling during producing of inner parity information and outer parity information by the RS coding can be considered. In other words, the shuffling and the RS coding are coupled during a recording of digital data onto a magnetic tape, so that the method creates parity information for error correction corresponding to a predetermined size of data read in a scrambled time order from a memory in which the data are sequentially stored, and stores the parity information so as to be related with the data before being recorded onto the magnetic tape. The method of data shuffling distributes burst errors, so that error correction becomes easy.